I wrote a much more comprehensive reply to your above post but lost it because my Internet connection here went down. :(
To me it is worth it, but opinions may vary here since "worth" is subjective - what may be worthy to some may be worthless to others.
If you are concerned with safety of yourself AND others on the road that we all share then it must be worthy. I have been looking at systems for some time now and the biggest hang-up on the deal is how/where to mount the moniitor so that it does not attract the bottom-feeders who like to smash and grab. Thinking of a 2-camera wireless system - one camera for the rear of the truck and the other for the rear of the RV. Considering the options at tadibothers.com.